// SPDX-License-Identifier: GPL-2.0-only
/*
 * rtmutex API
 */
#include <linux/spinlock.h>
#include <linux/export.h>

#include "_private_/rtmutex.c"

/*
 * Max number of times we'll walk the boosting chain:
 */
int max_lock_depth = 1024;

/*
 * Debug aware fast / slowpath lock,trylock,unlock
 *
 * The atomic acquire/release ops are compiled away, when either the
 * architecture does not support cmpxchg or when debugging is enabled.
 */
static __always_inline int __rt_mutex_lock_common(struct rt_mutex *lock,
                                                  unsigned int state,
                                                  struct lockdep_map *nest_lock,
                                                  unsigned int subclass)
{
    int ret;

    might_sleep();
    mutex_acquire_nest(&lock->dep_map, subclass, 0, nest_lock, _RET_IP_);
    ret = __rt_mutex_lock(&lock->rtmutex, state);
    if (ret)
        mutex_release(&lock->dep_map, _RET_IP_);
    return ret;
}

void rt_mutex_base_init(struct rt_mutex_base *rtb)
{
    __rt_mutex_base_init(rtb);
}
EXPORT_SYMBOL(rt_mutex_base_init);

#ifdef CONFIG_DEBUG_LOCK_ALLOC
/**
 * rt_mutex_lock_nested - lock a rt_mutex
 *
 * @lock: the rt_mutex to be locked
 * @subclass: the lockdep subclass
 */
void __sched rt_mutex_lock_nested(struct rt_mutex *lock, unsigned int subclass)
{
    __rt_mutex_lock_common(lock, TASK_UNINTERRUPTIBLE, NULL, subclass);
}
EXPORT_SYMBOL_GPL(rt_mutex_lock_nested);

void __sched _rt_mutex_lock_nest_lock(struct rt_mutex *lock, struct lockdep_map *nest_lock)
{
    __rt_mutex_lock_common(lock, TASK_UNINTERRUPTIBLE, nest_lock, 0);
}
EXPORT_SYMBOL_GPL(_rt_mutex_lock_nest_lock);

#else /* !CONFIG_DEBUG_LOCK_ALLOC */

/**
 * rt_mutex_lock - lock a rt_mutex
 *
 * @lock: the rt_mutex to be locked
 */
void __sched rt_mutex_lock(struct rt_mutex *lock)
{
    __rt_mutex_lock_common(lock, TASK_UNINTERRUPTIBLE, NULL, 0);
}
EXPORT_SYMBOL_GPL(rt_mutex_lock);
#endif

/**
 * rt_mutex_lock_interruptible - lock a rt_mutex interruptible
 *
 * @lock:		the rt_mutex to be locked
 *
 * Returns:
 *  0		on success
 * -EINTR	when interrupted by a signal
 */
int __sched rt_mutex_lock_interruptible(struct rt_mutex *lock)
{
    return __rt_mutex_lock_common(lock, TASK_INTERRUPTIBLE, NULL, 0);
}
EXPORT_SYMBOL_GPL(rt_mutex_lock_interruptible);

/**
 * rt_mutex_lock_killable - lock a rt_mutex killable
 *
 * @lock:		the rt_mutex to be locked
 *
 * Returns:
 *  0		on success
 * -EINTR	when interrupted by a signal
 */
int __sched rt_mutex_lock_killable(struct rt_mutex *lock)
{
    return __rt_mutex_lock_common(lock, TASK_KILLABLE, NULL, 0);
}
EXPORT_SYMBOL_GPL(rt_mutex_lock_killable);

/**
 * rt_mutex_trylock - try to lock a rt_mutex
 *
 * @lock:	the rt_mutex to be locked
 *
 * This function can only be called in thread context. It's safe to call it
 * from atomic regions, but not from hard or soft interrupt context.
 *
 * Returns:
 *  1 on success
 *  0 on contention
 */
int __sched rt_mutex_trylock(struct rt_mutex *lock)
{
    int ret;

    if (IS_ENABLED(CONFIG_DEBUG_RT_MUTEXES) && WARN_ON_ONCE(!in_task()))
        return 0;

    ret = __rt_mutex_trylock(&lock->rtmutex);
    if (ret)
        mutex_acquire(&lock->dep_map, 0, 1, _RET_IP_);

    return ret;
}
EXPORT_SYMBOL_GPL(rt_mutex_trylock);

/**
 * rt_mutex_unlock - unlock a rt_mutex
 *
 * @lock: the rt_mutex to be unlocked
 */
void __sched rt_mutex_unlock(struct rt_mutex *lock)
{
    mutex_release(&lock->dep_map, _RET_IP_);
    __rt_mutex_unlock(&lock->rtmutex);
}
EXPORT_SYMBOL_GPL(rt_mutex_unlock);

/*
 * Futex variants, must not use fastpath.
 */
int __sched rt_mutex_futex_trylock(struct rt_mutex_base *lock)
{
    return rt_mutex_slowtrylock(lock);
}

int __sched __rt_mutex_futex_trylock(struct rt_mutex_base *lock)
{
    return __rt_mutex_slowtrylock(lock);
}

/**
 * __rt_mutex_futex_unlock - Futex variant, that since futex variants
 * do not use the fast-path, can be simple and will not need to retry.
 *
 * @lock:	The rt_mutex to be unlocked
 * @wqh:	The wake queue head from which to get the next lock waiter
 */
bool __sched __rt_mutex_futex_unlock(struct rt_mutex_base *lock,
                                     struct rt_wake_q_head *wqh)
{
    lockdep_assert_held(&lock->wait_lock);

    debug_rt_mutex_unlock(lock);

    if (!rt_mutex_has_waiters(lock))
    {
        lock->owner = NULL;
        return false; /* done */
    }

    /*
     * mark_wakeup_next_waiter() deboosts and retains preemption
     * disabled when dropping the wait_lock, to avoid inversion prior
     * to the wakeup.  preempt_disable() therein pairs with the
     * preempt_enable() in rt_mutex_postunlock().
     */
    mark_wakeup_next_waiter(wqh, lock);

    return true; /* call postunlock() */
}

void __sched rt_mutex_futex_unlock(struct rt_mutex_base *lock)
{
    DEFINE_RT_WAKE_Q(wqh);
    unsigned long flags;
    bool postunlock;

    raw_spin_lock_irqsave(&lock->wait_lock, flags);
    postunlock = __rt_mutex_futex_unlock(lock, &wqh);
    raw_spin_unlock_irqrestore(&lock->wait_lock, flags);

    if (postunlock)
        rt_mutex_postunlock(&wqh);
}

/**
 * __rt_mutex_init - initialize the rt_mutex
 *
 * @lock:	The rt_mutex to be initialized
 * @name:	The lock name used for debugging
 * @key:	The lock class key used for debugging
 *
 * Initialize the rt_mutex to unlocked state.
 *
 * Initializing of a locked rt_mutex is not allowed
 */
void __sched __rt_mutex_init(struct rt_mutex *lock, const char *name,
                             struct lock_class_key *key)
{
    debug_check_no_locks_freed((void *)lock, sizeof(*lock));
    __rt_mutex_base_init(&lock->rtmutex);
    lockdep_init_map_wait(&lock->dep_map, name, key, 0, LD_WAIT_SLEEP);
}
EXPORT_SYMBOL_GPL(__rt_mutex_init);

/**
 * rt_mutex_init_proxy_locked - initialize and lock a rt_mutex on behalf of a
 *				proxy owner
 *
 * @lock:	the rt_mutex to be locked
 * @proxy_owner:the task to set as owner
 *
 * No locking. Caller has to do serializing itself
 *
 * Special API call for PI-futex support. This initializes the rtmutex and
 * assigns it to @proxy_owner. Concurrent operations on the rtmutex are not
 * possible at this point because the pi_state which contains the rtmutex
 * is not yet visible to other tasks.
 */
void __sched rt_mutex_init_proxy_locked(struct rt_mutex_base *lock,
                                        struct task_struct *proxy_owner)
{
    static struct lock_class_key pi_futex_key;

    __rt_mutex_base_init(lock);
    /*
     * On PREEMPT_RT the futex hashbucket spinlock becomes 'sleeping'
     * and rtmutex based. That causes a lockdep false positive, because
     * some of the futex functions invoke spin_unlock(&hb->lock) with
     * the wait_lock of the rtmutex associated to the pi_futex held.
     * spin_unlock() in turn takes wait_lock of the rtmutex on which
     * the spinlock is based, which makes lockdep notice a lock
     * recursion. Give the futex/rtmutex wait_lock a separate key.
     */
    lockdep_set_class(&lock->wait_lock, &pi_futex_key);
    rt_mutex_set_owner(lock, proxy_owner);
}

/**
 * rt_mutex_proxy_unlock - release a lock on behalf of owner
 *
 * @lock:	the rt_mutex to be locked
 *
 * No locking. Caller has to do serializing itself
 *
 * Special API call for PI-futex support. This just cleans up the rtmutex
 * (debugging) state. Concurrent operations on this rt_mutex are not
 * possible because it belongs to the pi_state which is about to be freed
 * and it is not longer visible to other tasks.
 */
void __sched rt_mutex_proxy_unlock(struct rt_mutex_base *lock)
{
    debug_rt_mutex_proxy_unlock(lock);
    rt_mutex_clear_owner(lock);
}

/**
 * __rt_mutex_start_proxy_lock() - Start lock acquisition for another task
 * @lock:		the rt_mutex to take
 * @waiter:		the pre-initialized rt_mutex_waiter
 * @task:		the task to prepare
 * @wake_q:		the wake_q to wake tasks after we release the wait_lock
 *
 * Starts the rt_mutex acquire; it enqueues the @waiter and does deadlock
 * detection. It does not wait, see rt_mutex_wait_proxy_lock() for that.
 *
 * NOTE: does _NOT_ remove the @waiter on failure; must either call
 * rt_mutex_wait_proxy_lock() or rt_mutex_cleanup_proxy_lock() after this.
 *
 * Returns:
 *  0 - task blocked on lock
 *  1 - acquired the lock for task, caller should wake it up
 * <0 - error
 *
 * Special API call for PI-futex support.
 */
int __sched __rt_mutex_start_proxy_lock(struct rt_mutex_base *lock,
                                        struct rt_mutex_waiter *waiter,
                                        struct task_struct *task,
                                        struct wake_q_head *wake_q)
{
    int ret;

    lockdep_assert_held(&lock->wait_lock);

    if (try_to_take_rt_mutex(lock, task, NULL))
        return 1;

    /* We enforce deadlock detection for futexes */
    ret = task_blocks_on_rt_mutex(lock, waiter, task, NULL,
                                  RT_MUTEX_FULL_CHAINWALK, wake_q);

    if (ret && !rt_mutex_owner(lock))
    {
        /*
         * Reset the return value. We might have
         * returned with -EDEADLK and the owner
         * released the lock while we were walking the
         * pi chain.  Let the waiter sort it out.
         */
        ret = 0;
    }

    return ret;
}

/**
 * rt_mutex_start_proxy_lock() - Start lock acquisition for another task
 * @lock:		the rt_mutex to take
 * @waiter:		the pre-initialized rt_mutex_waiter
 * @task:		the task to prepare
 *
 * Starts the rt_mutex acquire; it enqueues the @waiter and does deadlock
 * detection. It does not wait, see rt_mutex_wait_proxy_lock() for that.
 *
 * NOTE: unlike __rt_mutex_start_proxy_lock this _DOES_ remove the @waiter
 * on failure.
 *
 * Returns:
 *  0 - task blocked on lock
 *  1 - acquired the lock for task, caller should wake it up
 * <0 - error
 *
 * Special API call for PI-futex support.
 */
int __sched rt_mutex_start_proxy_lock(struct rt_mutex_base *lock,
                                      struct rt_mutex_waiter *waiter,
                                      struct task_struct *task)
{
    int ret;
    DEFINE_WAKE_Q(wake_q);

    raw_spin_lock_irq(&lock->wait_lock);
    ret = __rt_mutex_start_proxy_lock(lock, waiter, task, &wake_q);
    if (unlikely(ret))
        remove_waiter(lock, waiter);
    preempt_disable();
    raw_spin_unlock_irq(&lock->wait_lock);
    wake_up_q(&wake_q);
    preempt_enable();

    return ret;
}

/**
 * rt_mutex_wait_proxy_lock() - Wait for lock acquisition
 * @lock:		the rt_mutex we were woken on
 * @to:			the timeout, null if none. hrtimer should already have
 *			been started.
 * @waiter:		the pre-initialized rt_mutex_waiter
 *
 * Wait for the lock acquisition started on our behalf by
 * rt_mutex_start_proxy_lock(). Upon failure, the caller must call
 * rt_mutex_cleanup_proxy_lock().
 *
 * Returns:
 *  0 - success
 * <0 - error, one of -EINTR, -ETIMEDOUT
 *
 * Special API call for PI-futex support
 */
int __sched rt_mutex_wait_proxy_lock(struct rt_mutex_base *lock,
                                     struct hrtimer_sleeper *to,
                                     struct rt_mutex_waiter *waiter)
{
    int ret;

    raw_spin_lock_irq(&lock->wait_lock);
    /* sleep on the mutex */
    set_current_state(TASK_INTERRUPTIBLE);
    ret = rt_mutex_slowlock_block(lock, NULL, TASK_INTERRUPTIBLE, to, waiter, NULL);
    /*
     * try_to_take_rt_mutex() sets the waiter bit unconditionally. We might
     * have to fix that up.
     */
    fixup_rt_mutex_waiters(lock, true);
    raw_spin_unlock_irq(&lock->wait_lock);

    return ret;
}

/**
 * rt_mutex_cleanup_proxy_lock() - Cleanup failed lock acquisition
 * @lock:		the rt_mutex we were woken on
 * @waiter:		the pre-initialized rt_mutex_waiter
 *
 * Attempt to clean up after a failed __rt_mutex_start_proxy_lock() or
 * rt_mutex_wait_proxy_lock().
 *
 * Unless we acquired the lock; we're still enqueued on the wait-list and can
 * in fact still be granted ownership until we're removed. Therefore we can
 * find we are in fact the owner and must disregard the
 * rt_mutex_wait_proxy_lock() failure.
 *
 * Returns:
 *  true  - did the cleanup, we done.
 *  false - we acquired the lock after rt_mutex_wait_proxy_lock() returned,
 *          caller should disregards its return value.
 *
 * Special API call for PI-futex support
 */
bool __sched rt_mutex_cleanup_proxy_lock(struct rt_mutex_base *lock,
                                         struct rt_mutex_waiter *waiter)
{
    bool cleanup = false;

    raw_spin_lock_irq(&lock->wait_lock);
    /*
     * Do an unconditional try-lock, this deals with the lock stealing
     * state where __rt_mutex_futex_unlock() -> mark_wakeup_next_waiter()
     * sets a NULL owner.
     *
     * We're not interested in the return value, because the subsequent
     * test on rt_mutex_owner() will infer that. If the trylock succeeded,
     * we will own the lock and it will have removed the waiter. If we
     * failed the trylock, we're still not owner and we need to remove
     * ourselves.
     */
    try_to_take_rt_mutex(lock, current, waiter);
    /*
     * Unless we're the owner; we're still enqueued on the wait_list.
     * So check if we became owner, if not, take us off the wait_list.
     */
    if (rt_mutex_owner(lock) != current)
    {
        remove_waiter(lock, waiter);
        cleanup = true;
    }
    /*
     * try_to_take_rt_mutex() sets the waiter bit unconditionally. We might
     * have to fix that up.
     */
    fixup_rt_mutex_waiters(lock, false);

    raw_spin_unlock_irq(&lock->wait_lock);

    return cleanup;
}

/*
 * Recheck the pi chain, in case we got a priority setting
 *
 * Called from sched_setscheduler
 */
void __sched rt_mutex_adjust_pi(struct task_struct *task)
{
    struct rt_mutex_waiter *waiter;
    struct rt_mutex_base *next_lock;
    unsigned long flags;

    raw_spin_lock_irqsave(&task->pi_lock, flags);

    waiter = task->pi_blocked_on;
    if (!waiter || rt_waiter_node_equal(&waiter->tree, task_to_waiter_node(task)))
    {
        raw_spin_unlock_irqrestore(&task->pi_lock, flags);
        return;
    }
    next_lock = waiter->lock;
    raw_spin_unlock_irqrestore(&task->pi_lock, flags);

    /* gets dropped in rt_mutex_adjust_prio_chain()! */
    get_task_struct(task);

    rt_mutex_adjust_prio_chain(task, RT_MUTEX_MIN_CHAINWALK, NULL,
                               next_lock, NULL, task);
}

/*
 * Performs the wakeup of the top-waiter and re-enables preemption.
 */
void __sched rt_mutex_postunlock(struct rt_wake_q_head *wqh)
{
    rt_mutex_wake_up_q(wqh);
}

/* Mutexes */
void __mutex_rt_init(struct mutex *mutex, const char *name,
                     struct lock_class_key *key)
{
    debug_check_no_locks_freed((void *)mutex, sizeof(*mutex));
    lockdep_init_map_wait(&mutex->dep_map, name, key, 0, LD_WAIT_SLEEP);
}
EXPORT_SYMBOL(__mutex_rt_init);

static __always_inline int __mutex_lock_common(struct mutex *lock,
                                               unsigned int state,
                                               unsigned int subclass,
                                               struct lockdep_map *nest_lock,
                                               unsigned long ip)
{
    int ret;

    might_sleep();
    mutex_acquire_nest(&lock->dep_map, subclass, 0, nest_lock, ip);
    ret = __rt_mutex_lock(&lock->rtmutex, state);
    if (ret)
        mutex_release(&lock->dep_map, ip);
    else
        lock_acquired(&lock->dep_map, ip);
    return ret;
}

void __sched mutex_lock(struct mutex *lock)
{
    __mutex_lock_common(lock, TASK_UNINTERRUPTIBLE, 0, NULL, _RET_IP_);
}
EXPORT_SYMBOL(mutex_lock);

int __sched mutex_lock_interruptible(struct mutex *lock)
{
    return __mutex_lock_common(lock, TASK_INTERRUPTIBLE, 0, NULL, _RET_IP_);
}
EXPORT_SYMBOL(mutex_lock_interruptible);

int __sched mutex_lock_killable(struct mutex *lock)
{
    return __mutex_lock_common(lock, TASK_KILLABLE, 0, NULL, _RET_IP_);
}
EXPORT_SYMBOL(mutex_lock_killable);

void __sched mutex_lock_io(struct mutex *lock)
{
    int token = io_schedule_prepare();

    __mutex_lock_common(lock, TASK_UNINTERRUPTIBLE, 0, NULL, _RET_IP_);
    io_schedule_finish(token);
}
EXPORT_SYMBOL(mutex_lock_io);

int __sched mutex_trylock(struct mutex *lock)
{
    int ret;

    if (IS_ENABLED(CONFIG_DEBUG_RT_MUTEXES) && WARN_ON_ONCE(!in_task()))
        return 0;

    ret = __rt_mutex_trylock(&lock->rtmutex);
    if (ret)
        mutex_acquire(&lock->dep_map, 0, 1, _RET_IP_);

    return ret;
}
EXPORT_SYMBOL(mutex_trylock);

void __sched mutex_unlock(struct mutex *lock)
{
    mutex_release(&lock->dep_map, _RET_IP_);
    __rt_mutex_unlock(&lock->rtmutex);
}
EXPORT_SYMBOL(mutex_unlock);
